This invention relates to antibiotic compositions suitable for pharmaceutical use. More particularly, it relates to aqueous solutions of tetracycline antibiotics in caprolactam or 2-piperidone.
U.S. Pat. No. 3,957,980 discloses aqueous injectable solutions of doxycycline comprising a solution in water of from about 1% to 10% by weight of doxycycline, together with about 3 to 8 molar proportions of a phosphate salt selected from phosphoric acid, sodium or potassium orthophosphate, metaphosphate, pyrophosphate, tripolyphosphate or hexametaphosphate, and about 3 to 8 molar proportions of a pharmaceutically acceptable magnesium salt solution in said aqueous pharmaceutical composition, said composition having a pH value in the range of from about 1 to 3.5.
U.S. Pat. No. 3,674,859 discloses aqueous solutions of doxycycline containing from about 1% to 15% doxycycline and from about 5 percent to 40 percent by weight of polyvinylpyrrolidone having an average molecular weight that is in the range of from about 10,000 to about 60,000, said composition having a pH value in the range of from about 5 to about 8.
U.S. Pat. No. 2,980,584 discloses aqueous parenteral solutions of oxytetracycline metal complexes containing 25-80% of an acetic or lactic acid carboxamide, such as N,N-dimethylacetamide and N-(.beta.-hydroxyethyl) lactamide at a pH of 8.5-9.5. Concentrations of 10 to 100 mg./ml. are disclosed.
U.S. Pat. No. 2,990,331 discloses parenteral solutions of oxytetracycline hydrochloride and tetracycline hydrochloride containing about 50 mg./ml. having a pH value between 5 and 7, containing magnesium ions, an alkali bisulfite and a carboxylic acid amide, such as lactic acid-hydroxyethyl amide.
U.S. Pat. No. 3,062,717 discloses aqueous parenteral solutions of tetracycline calcium complexes containing 35-80% of an amide of acetic or lactic acid, such as N,N-dimethylacetamide or N-(.beta.-hydroxylethyl) lactamide, at a pH of 7 to 9.5. Concentrations of 10 to 100 mg./ml. are disclosed.
U.S. Pat. No. 3,557,280 discloses aqueous solutions of oxytetracycline containing 1 to 20% oxytetracycline, a magnesium compound and polyvinylpyrrolidone, 7.5 to 25%, at a pH of 8.0 to 9.5.
Belgian Pat. No. 825,656 discloses aqueous solutions of oxytetracycline containing 4 to 11% oxytetracycline, 20 to 30% of a polyethylene glycol, such as polyethylene glycol 400, a magnesium compound and 0.10 to 0.35% of a buffer, such as tris-(hydroxymethyl)-amino-methane at a pH of 8 to 9.
French Patent Publication No. 2,258,187 discloses aqueous solutions of oxytetracycline containing 50 mg./ml. of oxytetracycline, 5 to 7.49% polyvinylpyrrolidone and up to 24.9% of an acid amide containing one to six carbon atoms, such as dimethylacetamide, at a pH of 8 to 9.5.
U.S. Pat. No. 4,018,889 discloses oxytetracycline solutions containing from about 1 to 40 percent oxytetracycline in an aqueous vehicle containing from about 10 to 50 percent by weight of 2-pyrrolidone, about 0.8 to 1.3 molar proportions of a pharmaceutically acceptable magnesium compound soluble in the said solution, said solution having a pH value in the range of from about 7.5 to 9.5.